Other language confidence: 0.9263933010885371
This dataset is supplemental to the paper Wallis et al. (2021) and contains data on dislocations and their stress fields in olivine from the Oman-UAE ophiolite measured by oxidation decoration, electron backscatter diffraction (EBSD) and high-angular resolution electron backscatter diffraction (HR-EBSD). The datasets include images of decorated dislocations, measurements of lattice orientation and misorientations, densities of geometrically necessary dislocations, and heterogeneity in residual stress. Data are provided as 6 TIF files, 8 CTF files, and 37 tab-delimited TXT files. Files are organised by the figure in which the data are presented in the main paper. Data types or sample numbers are also indicated in the file names.
These data files contain short periods of electrical data recorded at Stromboli volcano, Italy, in 2019 and 2020 using a prototype version of the Biral Thunderstorm Detector BTD-200. This sensor consists of two antennas, the primary and secondary antenna, which detect slow variations in the electrostatic field resulting from charge neutralisation due to electrical discharges. The sensor recorded at three different locations: BTD1 (38.79551°N, 15.21518°E), BTD2 (38.80738°N, 15.21355°E) and BTD3 (38.79668°N, 15.21622°E). Electrical data of the following explosions is provided (each in a separate data file): - Three Strombolian explosions on 12 June 2019 at 12:46:53, 12:49:27 and 12:56:10 UTC, respectively. - A major explosion on 25 June 2019 at 23:03:08 UTC. - A major explosion on 19 July 2020 at 03:00:42 UTC. - A major explosion on 16 November 2020 at 09:17:45 UTC. - A paroxysmal event at 3 July 2019 at 14:45:43 UTC. Each filename indicates the location of the BTD, the starting date and time of the file in UTC, and a short description of the three data columns inside the file (unixtime, primary, secondary). The first column provides the Unix timestamp of each data point, which is the time in seconds since 01/01/1970. All time is provided in UTC. The second column provides the measured voltage [V] recorded by the primary antenna. The third column provides the measured voltage [V] recorded by the secondary antenna.
This data publication provides data from 42 experiments from 2018 and 2019 in the Fragmentation Lab at the Ludwig-Maximilians University Munich (Germany). The experiments were taken out to analyse the influence of the water content and the initial temperature of the pre-experimental sample on the produced electrification in rapid decompression, shock-tube experiments. All samples used in this study are 90-300 μm loose ash samples from the lower Laacher See unit.To carry out this study, we have built up on previous studies by Cimarelli et al. (2014) and Gaudin & Cimarelli (2019b, dataset to be found in Gaudin & Cimarelli, 2019a). A sample of loose ash gets placed in an autoclave. In our study, we have added water in some experiments. Also, a furnace was often used to heat the sample to up to 320 °C. After both water addition and heating, the autoclave gets pressurized using argon gas. Once a target pressure of 9 MPa is reached, the experiment gets triggered by rupturing metal diaphragms, which rapid decompresses the sample and ejects it into a collector tank. This collector tank is made out of steel and electrically insulated from its surrounding, thus working as a Faraday cage (FC), which is able to detect the net charge within at any point during the experiment. We detect discharges on that net charge up to 10 ms after the ejection of the particles.This dataset contains:- an overview .xlsx file (ExperimentOverview) containing key information for the 42 experiments used for analysis in this study- raw .csv files for all experiments- .pdf files showing the key elements of the analysed experiments, incl. data from Faraday cage and pressure sensorsFor more information please refer to the data description and the associated publication (Stern et al., 2019).
The largest magnitude earthquakes nucleate at depths near the base of the seismogenic zone, near the transition from velocity weakening frictional slip to velocity strengthening ductile flow. However, the mechanisms controlling this transition, and relevant to earthquake nucleation, remain poorly understood. Here we present data from experiments investigating the effect of slip rate on the mechanical properties and microstructure development of simulated calcite fault gouge sheared at ~550°C, close to the transition from (unstable) velocity weakening to (stable) velocity strengthening behaviour, reported by Verberne et al. (2015).We conducted experiments at a constant effective normal stress (σneff) of 50 MPa, as well as σneff-stepping tests employing 20 MPa ≤ σneff ≤ 140 MPa, at constant sliding velocities (v) of 0.1, 1, 10, or 100 µm/s. Samples sheared at v ≥ 1 µm/s showed a microstructure characterized by a single, 30 to 40 μm wide boundary shear, as well as a linear correlation of shear strength (τ) with σneff. Remarkably, electron backscatter diffraction mapping of polygonal shear band grains demonstrated a crystallographic preferred orientation. By contrast, samples sheared at 0.1 µm/s showed a microstructure characterized by homogeneous deformation and plastic flow, as well as a flattening-off of the τ-σneff curve. Our results point to a strain rate dependent frictional-to-viscous transition in simulated calcite fault gouge, and have important implications for the processes controlling earthquake nucleation at the base of the seismogenic zone.
The spectacular water outburst occurring semi-periodically when the ice-dam formed by the external front of the Perito Moreno glacier collapses, is one of the most attracting events in the UNESCO ‘Parque Nacional Los Glaciares’ of southern Patagonia. These occurrences have been documented since 1936. Instead, evidence of previous events has been only indirectly provided by dendrochronology analysis. Four sediments cores have been collected on coastal soil in 2017, analysed by X rays, HR photography and Magnetic Susceptibility. The radiographies of these cores allowed to identify lake floodings deposits due to glacier readvance over the coastal soil related to the collapse of the Perito Moreno ice-dam. In November 2018, 10 undisturbed sediment gravity cores were collected within a small inlet of Brazo Sur, that is, the southern arm of Lago Argentino, at water depths ranging from 10 to 6 m using a 4.5 cm diameter gravity corer ‘KC Kajak Sediment Sampler’ Model 13.030. The length of these cores varies from 45 to 65 cm. X rays, HR photography and magnetic susceptibility provide the first evidence of an abrupt change in the stratigraphic record found at variable depths of 14–18 cm from the top of the cores, marked by a hiatus spanning ca. 3200 years, separating planar-laminated sediments below from an alternation of erosional and depositional events above it, indicating recurring high-energy conditions generated by the emptying of the lake basin, as well as ash layers observed in the longest cores. Radio carbon data collected on three of these cores record ice-daming in the Little Ice age, at 324-266 cal yrs BP. These well-preserved stratigraphic records highlight the key role of glaciolacustine deposits in reconstructing the glacial dynamics and palaeoclimate evolution of a glaciated region.
This data publication includes particle size distribution data of natural volcanic ash samples used as starting material for laboratory experiments simulating the aggregation/disaggregation of colliding volcanic ash particles. Full details of the experimental method can be found in Del Bello et. al. (2015) and in the data description file provided here.Here we report raw particle size distribution data obtained through separation analysis. Two types of volcanic ash were analysed: i) andesitic ash from the Sakurajima volcano (Japan), collected from July 2013 deposits (named Sak sample); ii) phonolitic ash collected from the basal fallout layer of the ~10 ka old Pomici Principali eruptive unit [Di Vito et al., 1999]) of the Campi Flegrei (named Ppa). For both compositions, 3 different starting materials were obtained by hand sieving the natural samples into three main particle size classes: (i) <32 μm, (ii) 32–63 μm, and (iii) 63–90 μm. For the phonolitic composition Ppa two additional starting materials were obtained by mixing the <32 μm and the 32–63 μm classes in known proportions. For each starting material, the grain size distribution of the sample was measured by a multiwavelength separation analyzer (LUMIReader®, https://www.lum-gmbh.com/lumireader_en.html). This device measures space and time resolved profiles of the transmitted light across the water-diluted sample (5% solid content) during sedimentation of particles. The cumulative volume-weighted particle size distribution is obtained from the extinction profiles using the multi-wavelength Particle size Analyser modulus (PSA). Details on the sample preparation procedure can be found in Detloff et al. (2006). For each measurement performed (see Table 1), a pdf file and a excel file are provided. The pdf file lists the analysis summary, including a description of the analysis settings and conditions, materials used, and distribution model adopted for the fit. It also provides graphs of the obtained volume weighted cumulative grain size distribution, and of the measured transmission profiles for each wavelength (870 nm, 630 nm and 470 nm, respectively). The Excel (*.xlsx format) file include 4 datasheets, listing the results (sheet name ending *_R) and the fit data (sheet names ending *_F01,*_F02, *_F03) obtained for the different instrument wavelength. In each datasheet the following data are listed in the columns: particle grain size (x3 in µm), volume weighted distribution (Q3(x) in %), Martin diameter (x3m in µm), volume weighted density distribution (q3(x) in 1/µm). The fit datasheets also include information on the fit such as distribution model used and distribution parameters (quantiles, median, standard deviation, span, etc..).A full list of the files included is given in List_of_files_DelBello et al 2017.pdf.
Here we report the raw data of the physical properties of carbonate samples collected along the Monte Maggio normal Fault (MMF), a regional structure (length ~10 km and displacement ~500 m) located within the active system of the Apennines (Italy). In particular, we report results coming from large cores (100 mm in diameter and up to 20 cm long) drilled perpendicular to the fault plane made of Calcare Massiccio (massive limestone) and Bugarone fm (limestone with 8.3 % of clay). From these large cores, we obtained smaller cores, 38 mm in diameter both parallel and perpendicular to the fault plane, that have been used for experiments. We have divided the rock samples in four categories following the fault architecture. The four structural domains of the fault are:1) the hangingwall (HW) made of Bugarone fm that is still preserved in some portions of the fault, 2) a Cemented Cataclasite (CC) and 3) a Fault Breccia (FB) that characterize the cataclastic damage zones and 4) the correspondent undeformed protolith of the footwall block made of Calcare Massiccio. Raw data reported here are those used for drawing Figures 5, 6, 8 and 9 of the paper “Physical and transport property variations within carbonate- bearing fault zones: Insights from the Monte Maggio Fault (central Italy)”, http://doi.org/10.1002/ 2017GC007097 by Trippetta et al. Dataset_Fig05.txt reports P- and S-wave velocities (in km/s) of the described samples at pressure from 0.1 MPa (ambient pressure) up to 100 MPa at ambient temperature in dry conditions and the corresponding Vp/Vs ratio. Experiments have been performed by using the permeameter at the HP-HT Laboratory of experimental Volcanology and Geophysics at INGV (Rome).Dataset_Fig06.txt reports permeability data (in m^2) on the same type of samples of fig05 for the same range of confining pressure at ambient temperature. Pore pressure values athletes each confining pressure step are indicated in the file. Data have been again acquired with the permeameter.Dataset_Fig08.txt reports P-wave velocity data (in km/s) vs depth (in m), recorded on the portion that crossed the Calare Massiccio fm of three boreholes drilled in the Apennines: Varoni 1, Monte Civitello 1 and Daniel1. Data have been obtained by digitalizing each pdf file of the boreholes mentioned above, that are available at http://unmig.sviluppoeconomico.gov.it/videpi/videpi.asp. Once digitalized, respect to the original pdf file, velocity data have been simply converted from um/f to km/s.Dataset_Fig09.txt reports values of the maximum, minimum and average values of Critical fault nucleation length (in m) at each corresponding depth (in m) and applied confining pressure (in MPa). Critical nucleation lengths have been calculated by using the equations described in the text of the Trippetta et al paper and by using the elastic parameters calculated from data reported here. Data on earthquakes-depth distribution of the 2009 L'Aquila sequence can be found on Chiaraluce et al. (2011).
We studied the effect of pore fluid chemistry on compaction creep in quartz sand aggregates, as an analogue for clean, highly porous, quartz-rich reservoir sands and sandstone. Creep is specifically addressed, because it is not yet well understood and can potentially cause reservoir compaction even after production has ceased. Going beyond previous work, we focused on fluids typically considered for pressure maintenance or for permanent storage, e.g. water, wastewater, CO2 and N2, as well as agents, such as AlCl3, a quartz dissolution inhibitor, and scaling inhibitors used in water treatment facilities and geothermal energy production. Uniaxial (oedometer) compaction experiments were performed on cylindrical sand samples at constant effective stress (35 MPa) and constant temperature (80 °C), simulating typical reservoir depths of 2-4 km. Insight into the deformation mechanisms operating at the grain scale was obtained via acoustic emission (AE) counting, and by means of microstructural study and grain size analysis applied before and after individual compaction tests.
We have performed experiments on a basalt from the Main Ethiopian Rift (Ethiopia) to assess its pre-eruptive conditions in the magma chamber. The files contain all the analyses performed on the starting material (basalt) and the run products, both for the glass and mineral phases. Several experiments were carried out at temperatures between 1080°C and 975°C, mostly at 2 kbar and under reduced conditions (IHPV). The age spectrum of the basalt used (40Ar/39Ar) is also presented. Details are provided in the associated data description file.
Steam-driven eruptions are explosions that frequently occur in volcanic and geothermal areas. They are powered by the sudden release and expansion of steam and liquid water trapped under high pressure within the pore spaces of host rocks. We have experimentally studied how the strength of rock hosting steam and liquid controls the nature of explosions based on examples from Lake Okaro (New Zealand). Specifically, we used experiments to estimate the relative amounts of energy that goes into breaking rock up, versus that required for ejecting particles upwards and outwards. Here we report the main methodological approach and results of petrophysical properties analyses, decompression experiments and estimation of explosivity of water, respectively.
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